Gravitational collapse predicts tight scaling relations between ICM and cluster mass, according to the so-called self-similar model [1]}, [2]}. Moreover, cosmological simulations predict that the scaled thermodynamical profiles of galaxy clusters are nearly universal [3]}. For these reasons, the ICM is a powerful tool to study the formation and evolution of galaxy clusters: deviation from the gravitational collapse predictions can be used to investigate non-gravitational physics, such as cooling and feedback from supernovae and active galactic nuclei (AGN).
